Puncture Resistance Research Articles

Conductive hydrogel as stress‐strain sensor for human motion monitoring

AbstractHydrogel‐based stress‐strain sensors have attracted immense attention recently for developing wearable electronic devices and health‐monitoring systems owing to their intrinsic soft characteristics and flexible nature. Developing hydrogel that has high conductivity, better mechanical performance, and elasticity is necessary for better analysis or getting accurate measurement data. Hence, this study focuses on the development of novel conductive hydrogels with enhanced mechanical, swelling, and sensing properties targeting the advancement of stress‐strain sensitive hydrogel sensors. Polyvinyl alcohol (PVA) and citric acid (CA) have been used to prepare esterified PVA/CA hydrogels while using a simple one‐pot method followed by doping with a conductive polymer (polyaniline, PANI). The resultant PVA/CA/PANI hydrogel displayed a high water uptake capacity of ∼4200%, a high mechanical strain of 700%, high puncture resistance, large durability, and a fast response time when applied as soft human‐motion sensors in real‐time measurement of large‐scale and subtle human physiological stress activities (i.e., joint motions in the forefinger, elbow, wrist, and neck). The high strain sensitivity and ultrahigh stretchability of hydrogel sensors allow them to detect small mechanical changes caused by human movement showing their great potential for hydrogel‐based sensor device fabrication.

Stiffness-switchable hydrogel composite for transformable exo-suit

Transformable exo-suits, which are soft and wearable under normal conditions and could increase stiffness dramatically on demand, are significant in personal protection and robotics and also a dream of science-fiction fans. Herein, an ideal candidate material based on a carbon fabric reinforced thermal-hardening hydrogel (CFRTH) composite is proposed for developing transformable exo-suits. The introduction of carbon fabric significantly enhances the mechanical performance of thermal-hardening hydrogel, and empowers the CFRTH composite with an active, rapid and repeatable stiffness switchability. At ambient temperature, the CFRTH composite developed is soft and wearable with excellent flexibility and shape adaptability, while the composite becomes hard and rigid instantaneously as temperature rises. The flexural modulus of the CFRTH composite increases from 2.3 MPa to 539.7 MPa (about 232 times) by applying an electro-thermal stimulus, which endows the composite with good energy absorption/dissipation performance. Compared with the untransformed CFRTH composite, the transformed CFRTH composite under the electro-thermal stimulus exhibits a giant improvement (200%) in the peak force attenuation ratio under dropping ball test and excellent puncture resistance under penetration test and knife stab. Finally, the transformable CFRTH composite demonstrates a high effectiveness in fragile product protection from the impact of steel ball. This study offers a novel and versatile strategy for developing transformable exo-suits which have wearable conformability under normal circumstances and exhibit enhanced stiffness and impact protection performance on-demand through an electro-thermal stimulus.

Bioinspired Nanolayered Structure Tuned by Extensional Stress: A Scalable Way to High-Performance Biodegradable Polyesters.

The nacre-inspired multi-nanolayer structure offers a unique combination of advanced mechanical properties, such as strength and crack tolerance, making them highly versatile for various applications. Nevertheless, a significant challenge lies in the current fabrication methods, which is difficult to create a scalable manufacturing process with precise control of hierarchical structure. In this work, a novel strategy is presented to regulate nacre-like multi-nanolayer films with the balance mechanical properties of stiffness and toughness. By utilizing a co-continuous phase structure and an extensional stress field, the hierarchical nanolayers is successfully constructed with tunable sizes using a scalable processing technique. This strategic modification allows the robust phase to function as nacre-like platelets, while the soft phase acts as a ductile connection layer, resulting in exceptional comprehensive properties. The nanolayer-structured films demonstrate excellent isotropic properties, including a tensile strength of 113.5MPa in the machine direction and 106.3MPa in a transverse direction. More interestingly, these films unprecedentedly exhibit a remarkable puncture resistance at the same time, up to 324.8Nmm-1, surpassing the performance of other biodegradable films. The scalable fabrication strategy holds significant promise in designing advanced bioinspired materials for diverse applications.

A strategy to prolong cheese shelf-life: Laminated films of bacterial cellulose and chitosan loaded with grape bagasse antioxidant extract for effective lipid oxidation delay

This study presents an innovative approach to developing bioactive composite films for food packaging applications. Laminated films composed of bacterial cellulose (BC) and chitosan were enriched with grape bagasse extract (GE) and glycerol. GE provides antioxidant capacity. Glycerol was added as plasticizer. The formulations were systematically varied to assess their mechanical and thermal properties. The assembly of the films demonstrated robust interaction between components, resulting in enhanced mechanical strength. Tensile tests revealed that GE and glycerol concentrations significantly influenced the tensile strength and elongation properties Films were obtained with Tensile Strength values that ranged between 16.92 and 32.71 MPa, but with an increase of up to 4 times in the percentage of elongation (from 2.33 to 8.63%) compared to films without GE. Puncture tests indicated that the incorporation of GE and glycerol played pivotal roles in improving puncture resistance. Predictive models were developed for better understanding. The laminated films were applied as separators for Havarti cheese, demonstrating their ability to mitigate lipid oxidation and maintaining antioxidant properties during storage. After 60 days of cheese storage, 67.3% decrease in the lipid oxidation was obtained. The findings suggest that laminated BC-chitosan films enriched with GE and glycerol could serve as effective, eco-friendly packaging materials with enhanced mechanical strength and antioxidant functionality for extending the shelf life of food products.

Andiroba Oil (Carapa guianensis Aubletet) as a Functionalizing Agent for Titica Vine (Heteropsis flexuosa) Nanofibril Films: Biodegradable Products from Species Native to the Amazon Region

The diversity of species in Amazonia is exceptionally vast and unique, and it is of great interest for industry sectors to explore the potential of derivatives with functional properties for packaging applications. This study proposes the functionalization of cellulose micro/nanofibril (MFC/NFC) suspensions from Heteropsis flexuosa with andiroba oil to produce films with packaging potential. MFC/NFC was produced by using mechanical fibrillation from suspensions of H. flexuosa fibers. Proportions of 1, 3, and 5% of andiroba oil were added to make films with concentrations of 1% (m/m). Suspensions with andiroba oil provided greater viscosity, with changes in the physical properties of the films. Functionalization with andiroba oil provided films with lower degradation in water, greater contact angle, and lower wettability despite high permeability to water vapor. The films with 1% andiroba oil showed a hydrophobic characteristic (contact angle > 90°) and greater puncture resistance (6.70 N mm−1). Films with 3% oil showed a more transparent appearance and high biodegradation, while 1% oil generated more opaque films with a higher thermal degradation temperature and high antioxidant activity. It was concluded that films produced from H. flexuosa fibers functionalized with andiroba oil showed packaging potential for light, low-moisture products due to their adequate thermal and barrier characteristics.

Engineering Rapeseed Germination and Root Growth with Mechanical Strength of Polysaccharide Hydrogel.

Plant roots are highly sensitive to physical stress in the soil, with appropriate mechanical impedance promoting root elongation and lateral root growth. However, few studies have quantitatively explored the relationship between the mechanical impedance of the growth medium and the phenotypes of plant roots. In this study, we used a tensile machine equipped with a self-made steel needle mimicking the root tip to measure the force needed to penetrate the hydrogel medium (agar, low acyl gellan gum, and κ-carrageenan), providing insights into the force required for the rapeseed root tip to enter the medium following germination. These findings indicate that root penetration length is inversely associated with the mechanical strength of the growth medium, with variations observed in the root system adaptability across different substrates. Specifically, when the gel puncture resistance of the culture medium without adding MS reached approximately 18.4 mN, root penetration and growth were significantly hindered. With the addition of 1/2 MS medium, the polysaccharide concentration is 1.0 wt %, which is more suitable for cultivating rapeseed. This research not only offers a method for quantifying root phenotypes and medium mechanical impedance but also presents an approach for plant growth regulation and crop breeding.

Enhancing Mechanical Properties of Corn Bran Arabinoxylan Films for Sustainable Food Packaging.

Arabinoxylan (AX)-based films can improve the mechanical characteristics of biodegradable materials when utilized for food packaging. However, the mechanical properties of AX films for food packaging applications require thorough investigation to establish their viability. In this study, AX was extracted from corn bran coproducts of dry-milling (DCB), wet-milling (WCB), and dried distiller's grains with solubles (DDGS) using an acid-alkali method. Packaging materials were produced using these AX extracts, each combined with laccase and sorbitol, forming the basis for three different films. These films were then modified by immersing the surface in a lipase-acetate solution. We evaluated their mechanical characteristics, including thickness, tensile properties, tear resistance, and puncture resistance. The thickness and tensile properties of the modified AX films derived from DCB and DDGS showed significant improvements (p < 0.05) compared to the unmodified AX films. In contrast, the modified AX films from WCB showed no significant changes (p > 0.05) in thickness and tensile properties compared to the unmodified WCB AX films. A significant increase in tear resistance (p < 0.05) was observed in all modified AX films after immersion in the lipase-acetate mixture. While puncture resistance was enhanced in the modified AX films, the improvement was not statistically significant (p > 0.05) compared to the unmodified films. The presence of hydroxyl (OH) and carbonyl (CO) groups on the surfaces of AX films from DCB and DDGS, modified by the lipase-acetate solution, suggests excellent biodegradability properties. The modification process positively affected the AX films, rendering them more bendable, flexible, and resistant to deformation when stretched, compared to the unmodified AX films.

Silkworm cocoon-inspired and robust nanofibrous composite separator with gradient structure for lithium ion batteries

Considering electrospun nanofiber-based membranes that generally exhibit high porosity but poor mechanical property, there is a growing need to fabricate nanofibrous separators with comprehensive performance for lithium-ion batteries (LIBs). Silkworm cocoon, a source of design inspiration from nature, comprises a multilayer structure with composition change in the thickness direction, thereby endowing the cocoon with relatively high porosity and outstanding mechanical strength. Therefore, a silkworm cocoon-like structured nanofibrous separator (GPS) is fabricated in this work by initially preparing several polyacrylonitrile (PAN) nanofibrous membranes with varied content of carboxyl styrene butadiene latex (SBR) and then laminating them in a concentration gradient sequence. Compared with the pristine PAN membrane, the GPS exhibits comparable porosity, thermal stability and electrolyte wettability due to the existence of PAN nanofibers, while the tensile strength and puncture resistance of the GPS are greatly raised by 5.5 times and 1.5 times, respectively. On account of the structure design, GPS also shows better mechanical strength than PAN/SBR separators without concentration gradient, and the strengthening mechanism has been verified by the finite element analysis. Meanwhile, such gradient structure of GPS renders the battery with desirable ion transport ability and stable cycle properties. Thus, the silkworm cocoon-like structured separator could be a promising separator candidate for LIBs, and the bioinspired design in structure will play an increasingly important role in the development of high-performance battery in the future.

Comparison of mechanical and comfort properties of natural fiber-based spacer fabrics for shoe insole

The objective of this study is to develop an improved shoe insole that enhances heat and moisture transmission (thermo-physiological comfort) qualities, as well as its mechanical characteristics, through the utilization of weft knitting spacer fabric. Two samples were prepared. One sample was comprised of Tri-Blend knitted fabric layers, while the other sample was made using cotton knitted fabrics in both layers. These layers, in both samples, were connected by spacer yarns of monofilament nylon. Tri-blend fabric was made from Bamboo (80%), flax (15%), and polypropylene (5%). Monofilament nylon was used in spacer layer. Thermo-physiological comfort testing i.e., air permeability, moisture management and thermal resistance test were performed for all the samples. The investigation also established the correlation between the mechanical properties, such as puncture resistance and tactile comfort, of footwear materials and their interaction with the human body. The prepared samples of shoe insole were also compared with the commercially available insoles made from synthetic materials. The outcome of the study suggests that the natural fiber spacer fabric can be used as an alternative to rubber. In conclusion, the results of this study offer valuable insights for product developers seeking sustainable alternatives that can meet consumer demands for both wearability and comfort.

Multi-layer material combination for manufaturing stab-proof life jackets

In modern times, individuals working in aquatic environments such as fishermen, fishery inspectors, customs officers, and others require a device that offers protection against punctures and drowning. As a result, a multi-layer composite material consisting of para-aramid 200de woven fabric, Dyneema® SB31 coated plates, and foam was evaluated for the creation of a life jacket that combines stab-proof capabilities with anti-drowning features (stab-proof life jacket). The objective of the research was to determine the optimal number of layers and arrangement of the multi-layer composite materials that would meet the NIJ standard level 1 protection against punctures. The study findings demonstrated that utilizing both types of woven fabric and coated plates yielded the most desirable puncture resistance, considering the thickness and weight of the composite materials. The effectiveness of using only woven fabric ranked second, while relying solely on coated plates produced less satisfactory results. Placing the puncture-resistant material above the foam layer proved to be more effective than placing it beneath the foam layer in all three scenarios. These findings lay the groundwork for the design and development of stab-proof life jackets tailored to the needs of professionals in specific aquatic industries. Keywords: Puncture-resistant life vest, puncture-resistant, multi-layer composite, aramid, UHMWPE

A fluorine-based strong and healable elastomer with unprecedented puncture resistance for high performance flexible electronics

There is usually a trade-off between high mechanical strength and dynamic self-healing because the mechanisms of these properties are mutually exclusive. Herein, we design and fabricate a fluorinated phenolic polyurethane (FPPU) elastomer based on octafluoro-4,4′-biphenol to overcome this challenge. This fluorine-based motif not only tunes interchain interactions through π−π stacking between aromatic rings and free-volume among polymer chains but also improves the reversibility of phenol-carbamate bonds via electron-withdrawing effect of fluorine atoms. The developed FPPU elastomer shows the highest recorded puncture energy (648.0 mJ), high tensile strength (27.0 MPa), as well as excellent self-healing efficiency (92.3%), along with low surface energy (50.9 MJ m−2), notch-insensitivity, and reprocessability compared with non-fluorinated counterpart biphenolic polyurethane (BPPU) elastomer. Taking advantage of the above-mentioned merits of FPPU elastomer, we prepare an anti-fouling triboelectric nanogenerator (TENG) with a self-healable, and reprocessable elastic substrate. Benefiting from stronger electron affinity of fluorine atoms than hydrogen atoms, this electronic device exhibits ultrahigh peak open-circuit voltage of 302.3 V compared to the TENG fabricated from BPPU elastomer. Furthermore, a healable and stretchable conductive composite is prepared. This research provides a distinct and general pathway toward constructing high-performance elastomers and will enable a series of new applications.

Analysis of Mechanical Properties of EVOH/LDPE Films Produced with Waste EVOH and LDPE

The importance of plastic materials continues to develop more and more every year from past to present. As important as the plastics used in almost every area of life are, it is equally important to keep these materials in the environmental cycle. Since 1970, the use and consumption of plastic has increased almost 10 times. A large share of the use of these plastics occurs in the flexible packaging sector. In the multi-layer films used on flexible packaging in the packaging industry, one of the most important issues of the future is the crisis of raw materials, and the other is recycling and sustainability. In this study, it is aimed to evaluate the low density polyethylene/ poly(ethylene-co-vinyl alcohol)/low polyethylene (LDPE/EVOH/LDPE) structured flexible packaging film waste produced by multilayer blown extrusion method within the same LDPE/EVOH/LDPE flexible packaging film and to examine the mechanical property changes of the material. Sustainable environment and economy, reducing the cost of raw materials, obtaining approximately similar mechanical properties are among the objectives of the study. The wastes released from the LDPE/EVOH/LDPE film were granulated in a single screw extruder. Then, the amount of these waste EVOH granules was 5%, 10%, 20% and 25% by weight in the total film, and their production was carried out with reference to the pure EVOH film in a 7-layer blown film extruder. Samples were taken from the films produced in 50µm thickness in accordance with the standards. Tensile test, tear test, puncture resistance test, sealing force test, shrinkage tests were performed. According to the results of the tests, analyzes on the use of scrap EVOH were concluded.

Biopolymeric corneal lenticules by digital light processing based bioprinting: a dynamic substitute for corneal transplant

Digital light processing (DLP) technology has gained significant attention for its ability to construct intricate structures for various applications in tissue modeling and regeneration. In this study, we aimed to design corneal lenticules using DLP bioprinting technology, utilizing dual network bioinks to mimic the characteristics of the human cornea. The bioink was prepared using methacrylated hyaluronic acid and methacrylated gelatin, where ruthenium salt and sodium persulfate were included for mediating photo-crosslinking while tartrazine was used as a photoabsorber. The bioprinted lenticules were optically transparent (85.45% ± 0.14%), exhibited adhesive strength (58.67 ± 17.5 kPa), and compressive modulus (535.42 ± 29.05 kPa) sufficient for supporting corneal tissue integration and regeneration. Puncture resistance tests and drag force analysis further confirmed the excellent mechanical performance of the lenticules enabling their application as potential corneal implants. Additionally, the lenticules demonstrated outstanding support for re-epithelialization and stromal regeneration when assessed with human corneal stromal cells. We generated implant ready corneal lenticules while optimizing bioink and bioprinting parameters, providing valuable solution for individuals suffering from various corneal defects and waiting for corneal transplants.

Fabrication of flame retardant nylon 6 film composites with superior gas barrier property and puncture resistance

Developing a flame retardant and puncture resistant nylon 6 (PA6) film composite with excellent gas barrier property as a food packaging material is still a great challenge. Herein, microencapsulation and hydrogen-bonding interaction were adopted to synthesize a multifunctional additive (SiO2@CS@GO-S), which simultaneously improved the mechanical, gas barrier and flame retardant performances of PA6 film. The obtained results indicated that the gas barrier property of the as-prepared PA6 film composite containing 0.1 wt% SiO2@CS@GO-S (PA6/SiO2@CS@GO-S-0.1) was obviously improved. For instance, the oxygen transmission rate of the film composite decreased dramatically by 52.0% compared with that of PA6 film. Furthermore, the puncture resistance of the PA6/SiO2@CS@GO-S-0.1 markedly increased from 18.3 N of PA6 to 25.3 N. Additionally, both thermal stability and fire safety of the PA6/SiO2@CS@GO-S film composites were enhanced. The peak of heat release rate and total smoke release of the PA6/SiO2@CS@GO-S-0.1 were reduced by 10.7% and 19.3%, respectively, compared to those of PA6 film. This work provides a new paradigm for creating a multifunctional PA6 film composite with high performance for grain preservation and loss reduction.

Neural Network‐Inspired Polyurea Ionogel with Mechanical Robustness, Low Hysteresis, and High Transparency for Soft Iontronics

AbstractConcurrently achieving mechanical robustness, low hysteresis, and high transparency are essential for ionogels to enhance their reliability and satisfy the requirements in soft electronics. Fabricating ionogels comprising these characteristics presents a considerable challenge. Herein, inspired by the structure of neural networks, a new strategy for in situ formation of dense urea moieties aggregated domains is proposed to achieve topology‐tailoring polyurea ionogels. Initially, leveraging the pronounced disparity in reactivity of the isocyanate (─NCO) groups between isophorone diisocyanate (IPDI) and NCO‐terminated prepolymer (PPGTD), IPDI preferentially reacts with deblocked trifunctional latent curing agents, resulting in the formation of dense urea moieties aggregated domains. Thereafter, these domains are interconnected via PPGTD to establish polymer networks in which the ionic liquid is uniformly dispersed, forming neural networks like ionogels. Attributed to this unique design strategy, the polyurea ionogel demonstrates remarkable properties, including high strength (0.6–2.4 MPa), excellent toughness (0.9–4.3 MJ m−3), low hysteresis (6.6–11.6%), high transparency (&gt;92%), along with enhanced fatigue and puncture resistance. Furthermore, the polyurea ionogels exhibit outstanding versatility, enabling their in strain sensors, flexible electroluminescence devices, and nanogenerators. This strategy contributes to the design of ionogels with unparalleled combinatory properties, catering to the diverse demands of soft iontronics.

Effects of Mosquito-Imitated Microneedle’s Reciprocating Rotations on Puncture Resistance Forces—Evaluations by Puncturing Experiments and Nonlinear FEM Analyses—

Development of a low-invasive microneedle is currently desired in the medical field to mitigate the patients’ stress and pain. We have paid attention to mosquitoes that puncture the skin without giving humans no feelings of pain. We have observed mosquitoes and found that when their proboscis punctures human skin, they make the following three behaviors: apply tension to human skin; rotate their proboscis; vibrate their proboscis. In our previous studies, we developed a bundled set of three microneedle imitating the mosquito’s proboscis and experimentally proved the usefulness of their alternate vibrations, which is one of the mosquito’s puncturing behaviors. However, the setting of three needles with proper clearances from each other was difficult, making their driving system too complex to practically use it. Therefore, we have developed a simplified microneedle by reducing the number of needles from three to two or one. This paper has focused on the effects of the rotations of a single needle. Using our developed microneedle with a diameter of 90 µm and the thinnest commercial microneedle with a diameter of 180 µm, we evaluated the effect of reciprocating rotation, one of the mosquitoes’ puncturing behaviors, by puncture experiments using artificial skin and nonlinear finite element method (FEM) analysis. As a result, it was found that the reciprocating rotation suppresses the puncture resistance force and the skin deflection.

Ultra-Tough, highly stable and Self-Adhesive Goatskin-Based intelligent Multi-Functional organogel e-skin as Temperature, Humidity, Strain, and bioelectric four-mode sensors for health monitoring

The rapid development of intelligent electronics has facilitated the transition of electronic devices from rigid systems to flexible ones. Flexible electronic skin (E-skin) that mimics natural biologic skin has attracted widespread attention owing to its significant applications in health management, soft robotics, human–machine interaction, etc. However, the increasing demand for more advanced functionalities imposes higher requirements on E-skin, such as high mechanical strength, flexibility, and biocompatibility. Herein, a top-down strategy was adopted to prepare a multifunctional organogel-based E-skin by using flexible but tough goatskin as the basic framework followed by the filling treatment with a poly(methacrylic acid-acrylamide) (P(MAA-co-AM)) network. This organogel exhibited excellent mechanical strength and puncture resistance, with fracture stress of 3.86 MPa and breaking elongation of 230 %, respectively, thus serving as the second skin layer to protect human body. Unlike conventional water-containing hydrogels, this organogel possessed exceptional biocompatibility and environmental stability, enabling it to operate normally at low temperature (e.g. −20 °C) and after long-term storage (˃ 15 d). More importantly, the crucial properties for practical application, such as adhesion, conductivity, and antibacterial performance, have been integrated into this organogel. A flexible, stretchable, and durable organogel-based sensor was further developed that can accurately monitor large-scale movements and subtle physiological signals of human body within a wide range of temperature and duration. Moreover, it could simultaneously achieve temperature, humidity, strain, and bioelectricity responsiveness on the same platform. This four-mode sensing mechanism can effectively complement and calibrate human body's health data, thus realizing precise monitoring of human health conditions. This work provides a new approach to structural design, enhancement, and multifunctionality of intelligent E-skin, aiming to replicate or even surpass the performance of real animal skin.

Reusing Thermal Insulation Materials: Reuse Potential and Durability Assessment of Stone Wool Insulation in Flat Roofs

In the building renovation industry, a growing volume of discarded insulation materials, such as stone wool insulation, prematurely finds its way to landfills or incinerators after building demolitions. However, these materials often did not reach their complete service life potential, and the reuse of insulation materials is usually not considered in current building practices. This study provides a comprehensive overview of the potential challenges associated with repurposing stone wool insulation from existing flat roofs. By means of detailed assessments via dismantling and performance evaluations of collected stone wool insulation boards up to 28 years old, this research reveals the unavoidable damages that occur upon dismantling yet emphasizes that this does not impede reuse. While density and thermal performance remain stable over time, water absorption and mechanical stability are affected. In total, 48% of all short-term tests revealed an increase in water absorption, possibly due to hydrophobic substance degradation. Mechanical performances of aged SW insulation from flat roofs depend on various factors, with 43% and 33% of compression and puncture resistance tests, respectively, not meeting current standards. Beyond a durability assessment, this study advocates for a multidisciplinary approach, uniting materials science, construction engineering, and sustainability insights, to creatively repurpose used insulation materials into future projects.

Characterization of the Mechanical, Biodegradation, and Morphological Properties of NBR/Biopolymer Blend, Integrated with a Risk Evaluation.

Biopolymer blends have attracted considerable attention in industrial applications due to their notable mechanical properties and biodegradability. This work delves into the innovative combination of butadiene-acrylonitrile (referred to as NBR) with a pectin-based biopolymer (NGP) at a 90:10 mass ratio through a detailed analysis employing mechanical characterization, Fourier transform infrared (FTIR) analysis, thermogravimetric analysis (TGA), and morphology studies using SEM. Additionally, biopolymer's biodegradability under aerobic and anaerobic conditions is tested. The study's findings underscore the superior tensile strength and elongation at break of the NGP/NBR blend in comparison to pure NBR, while also exhibiting a decrease in puncture resistance due to imperfect bonds at the particle-matrix interfaces, necessitating the use of a compatibilizer. In anaerobic conditions, evaluation of biodegradable properties reveals 2% and 12% biodegradability in NBR and NGP/NBR blend, respectively. The degradation properties were also aligned with TGA results highlighting a lower decomposition temperature for NGP. Additionally, this research integrates the application of a conditional value-at-risk (CVaR)-based analysis of the blend's tensile properties to evaluate the uncertainty impact in the experiment. Under risk, a significant enhancement in the tensile performance (by 80%) of the NGP/NBR blend was shown compared to pure NBR. Ultimately, the study shows that adding pectin to the NBR compound amplifies the overall performance of the biopolymer significantly under select criteria.

A comparative study of physical properties of nonwoven fabrics produced by uni- and bi-directional needles using response surface methodology

In the production of needle-punched nonwoven fabrics, the direction of needle barbs is towards the tip of the needle. When the needle penetrates into the fabric, the barbs carry some fibres into the fabric and when it returns the barbs are empty. This means that, the needle works when it penetrates into the fabric and doesn’t work when it returns. Using a bi-directional barb needle in the needle-punch process was proposed as an idea with the theory that, the needle also works when returning (leaving the layer). This study investigates the physical properties of needle-punched nonwoven fabrics produced with unidirectional and bi-directional needle types. Effects of needle penetration depth (NPD), strokes per minute (SPM), and needle type (N1, N2) on properties such as gram per square meter (GSM), thickness, fabric density (FD), and static puncture resistance (SPR) are examined. An experiment with 19 runs was designed using response surface methodology and optimal design with two quantitative factors, including NPD and SPM, and one qualitative factor containing needle types. In addition, four responses were measured and reported, including GSM, thickness, FD, and SPR. Test results show that needle N2 produces a fabric with lower FD, higher GSM, thickness, and SPR in comparison to needle N1, and was selected in optimization process with a desirability value of 0.872 against 0.688 for needle N1. The improved fabric properties of needle N2 may be exploited for the economic benefits of the nonwoven fabric producers or textile industry.